(1) Field of the Invention
The present invention relates to the display device having a resin substrate and Thin Film Transistors formed by oxide semiconductors.
(2) Description of the Related Art
The liquid crystal display device has a Thin Film Transistor (herein after TFT) in each of the pixels to control retrieving the data for the pixel. Sometimes, the built in driving circuit is made by TFTs.
The organic EL display device has a first TFT and a second TFT in each of the pixels. The first TFT is a switching TFT that controls retrieving the data to the pixel. The second TFT is a driving TFT that controls the current to the light emitting element. Sometimes, the built in driving circuit is made by TFTs.
Since a leak current in the oxide semiconductor is low, the display device of low power consumption can be realized by using the oxide semiconductors for the TFTs. In addition, a low leak current in the TFTs is profitable for the displays devices driven by low frequency.
Patent document 1 (Japanese patent laid open No. 2013-175718) and Patent document 2 (Japanese patent laid open No. 2011-54812) disclose a TFT having an oxide semiconductor. Patent document 1 discloses a top gate type TFT wherein the metal oxide is formed on the channel, which is formed by the oxide semiconductor, to constitute the gate insulating film. Patent document 1 discloses a bottom gate type TFT, which has an oxide semiconductor, wherein a metal oxide or a semiconductor layer is used as a sacrificing layer in the channel etching process.